Oil burner



A. CLARKSQN OIL BURNER April 2, 1940.

Filed Nov. 15, 1937 2 Shee ts-S heet 1 I fill/e afar/@900 April 1940- A. CLARKSON 2,195,617

on. BURNER I Filed Nov. 15, .1937 i 2 Sheets-Sheet 2 Infleniar Alia% [Z a/9012 L or n eys Patented Apr. 2; 1940 UNITED STATES PATENT OFFICE 8 Claims.

This invention relates to certain new and useful improvements in an oil burner, and more particularly to an improved process and apparatus for burning medium grades of liquid fuel, such as Diesel fuel oil, with a blue clean flame that has an outer envelope of air so that carbon is not formed when the flame is apparently in contact with cold metal surfaces.

Briefly described, the apparatus comprises means for circulating hot non-combustible gases (preferably a small portion of the hot products of combustion from the combustion zone) in intimate contact with the liquid fuel, preferably in contact with the surface of an exposed shallow pool of the liquid fuel so as to vaporize a portion of the fuel and carry this vapor back to the combustion zone. More specifically the combustion air is caused to flow through the apparatus in such a manner as to enforce the circulation of the heated gases and flow with these gases to the combustion zone, while at the same time forming an outer envelope of air around the combustion zone to protect the metal surfaces.

The principal object of this invention is to provide an improved oil burning apparatus of the type briefly described hereinabove and disclosed more in detail in the specifications which follow. Another object is to provide an improved means for burning medium grades of liquid fuel. Another object is to provide means for vaporizing heavy liquid fuel by passing hot gases incapable of supporting combustion in intimate surface contact with the liquid.

Another object is to provide improved means for causing an equalized distribution of the hot gases in contact with the surface of the liquid fuel.

Another object is to provide means for maintaining the oil inlet below the carbonizing temn perature.

Another object is to provide improved means for cooling those portions of the burner assembly where the direct application of heat is undesirable. Y

5 Other objects and advantages of this invention will be more apparent from 'the following detailed description of one approved form of apparatus cons ructed and operating according to the principles of this invention.

In the accompanying drawings:

Fig. 1 is a central vertical section through an assembly for heating water, with the improved burner used in combination therewith, the housingof the burner being shown in vertical section 65 and the interior members in elevation.

' Fig. 2 is a plan view of the burner assembly on a larger scale, portions being broken away.

Fig. 3 is a central vertical section through the burner assembly taken substantially on the line 3-4 of Fig. 2. 5

Fig. 4 is a detail vertical section taken substantially on the line 4-4 of Fig. 3 but on a larger scale.

Referring first to Fig. 1, the burner assembly indicated generally at A is supported within the casing or standard B on which is carried the hotwater heater C. The top wall I of casing B is provided with an opening 2 communicating with the heating space 3 within the boiler or water heater C. The outer shell or housing 4 of the burner assembly A is suspended-by a plurality of brackets or hooks 5 carried by bolts 6 projecting downwardly from the top wall I of casing B in such a manner as to clamp the deflector ring 1 between the upper edge of housing 4 and 20 wall I. The oil-pan 8 and bafile member 9 are centrally supported Within housing 4 (as hereinafter described more in detail). and the blower l0 suitably supported within the lower portion of casing B forces air through the opening H in the 25 bottom of housing 4 and thence around pan 8 and baflle 9 to the mixing and combustion zone l2 between deflector ring 7 and the top of baflle 9. In this zone the air mixed with vaporized fuel is ignited and the products of combustion 30 are directed inwardly and upwardly as indicated by the arrows through heating chamber 3. A smallportion of these heated gases are drawn inwardly and downwardly through baflle 9 (as hereinafter described) in order to vaporize the 35 oil.

The water-heater 0 comprises an inner shell l3 surrounding heating chamber 3, and an outer shell I4, and the water to be heated is confined in the annular space I5 between shells l3 and 40 14. The cold water flows in through a lower pipe 16 and the heated water is drawn off through an upper pipe H. The assembly is enclosed by an outer shell or covering l8, and the space between shells l4 and I8 is filled with suitable in- '45 sulation l9 so as to minimize the heat loss.

A deflector tube 20 is supported by the cover plate 2| and projects centrally downward into heater chamber 3. A plurality of fingers or other projections 22 extend inwardly from the 5 wall of inner casing l3 toward deflector tube 20 so as to provide an extended heat-transfer surface. The heated gases must flow upwardly through the annular space into which members 22 project so that a maximum of heat is transferred to casing l3 and thence to the water in space I5. The gases, thus relieved of the greater portion of their heat, then flow inwardly through ports 23 in the upper portion oftube and out through passage 24.

It will be understood that this particular type of hot-water heater forms no part of the present invention and is merely shown as one ex ample of a suitable apparatus to be heated by the burner assembly A which will now be described more in detail, referring also to Figs. 2 and 3-.

The pan 8 which holds the liquid fuel is of .Lrallow dished formation and is supported within the lower portion of housing 4 by a plurality of adjustable screws 25 projecting through the side walls of the housing and engaging the pan beneath the outstanding flange 28 at its upper edge. The pan will be centered within the housing so as to provide a small annular passage 21 through which the airforced into the lower portion of housing 4 through opening ll flows upwardly. A shallow pool of oil'or other liquid fuel 28 is maintained within pan 8, this pool being kept at a substantially constant level as indicated at :r. The oil is supplied through pipe 28 (see Fig. 1) from a constant source of supply to a suitable float-trap 30 in which a small supply of oil at constant level is maintained. The oil is delivered from device 38 through pipe 3|, metering valve 32, and pipe 33, extending through the lower portions of housing 4 and pan 8' into the well 34 at the center of pool 28. The specific construction of pan 8 will be described more in detail hereinafter when the reasons therefor become more apparent.

The baflie member 8 is of annular form and comprises a metallic bowl-shaped shell 35 which enclosesthe bottom and outer side of the annulus, and an inner block 38 of refractory material formed with a central vertically extending opening 31. The baflle is supported in spaced relation above the pan 8 by means of a plurality of bolts 38 screwed downwardly through shell 35 and resting on an annular shelf 38 formed within the pan. The baflle is properly centered within housing 4 by means of a plurality (usually three) of adjustable bolts 48 threaded through the side walls of shell 38 and engaging the inner surface of housing 4. The baflle is constructed by first inserting shell 35 within the housing and properly adjusting the bolts 38 and 48. Shell 35 is then removed and the refractory block 38 cast within the shell over the bolt heads. This is a simple and convenient manner of properly and permanently centering the baffle within the assembly.

The lower surface of the metallic baflle-shell or bowl 35 slopes outwardly and upwardly from the central opening 31 at substantially the same inclination as the pan 8, and is then rounded upwardly at 4| to provide a passage 42 between the lower surface of the baflie and the upper edge portion of pan 8. The baflle shell then extends upwardly and is inclined slightly inwardly at 43, whereas the housing 4 inclines outwardly so that the passage 44 between the baffle and housing has its narrowest portion directly above the juncture of the passages 21 and 42 and then flares or expands towards its top to provide an annular venturi. The air forced upwardly through passage 21 from beneath the pan and projected into this venturi will exert a suction through passage 42 so as to draw gases from the space between the pan and baflle. The upper surface 45 of the refractory block 38 of the baille inclines upwardly and inwardly so as to provide an annular flaring mixing chamber and combustion zone l2. It is in this space or zone that the vaporized fuel and air combine, that is where the ignition and combustion takes place.

Returning now to the description of pan 8, the upper surface thereof is provided with a circular series of grooves 41 extending radially, or more preferably curved all in the same direction from the central well 34. Just outside of these grooves are curved upstanding vanes 48 which at their higher outer ends may extend nearly into contact with the lower surface of baflie 3. The purpose of these vanes is to provide an extended heat-absorbing surface to expedite the vaporization of the oil, and also to impart a whirling movement and more equal distribution to the hot gases which are drawn downwardly onto the surface of the oil-pool 28-, and the vanes 48 and grooves 41 cooperate to produce an equalized distribution of vaporized fuel in the gas stream which is drawn outwardly through passage 42 into the venturi 44.

An annular layer of refractory insulating material 48 is held against the lower surface of the pan by means of a metallic cover plate 58 held in place by screws 51. This insulation tends to retain the heat applied by the hot gases to the upper surface of the shallow pool. However, it will be noted that the central portion 52 of the pan, which encloses the central well 34, is directly exposed to the cooling blast of air forced up from blower 10 so that this portion of the pan and oil-well will be maintained at a lower temperature, and the air blast also tends to cool the inlet pipe 33. In this manner the oil-inlet is maintained at a sufficiently low temperature to prevent carbonization at this point. The air stream also tends to cool the outer upwardly extending rim portion of pan 8.

In operation, combustion takes place in the zone l2 as already described, the greater portion of the hot combustion gases being drawn upwardly through the heating chamber 3 (Fig. 1), but a small portion of these hot combustion gases are drawn downwardly through the central opening 31 in the battle as indicated by the arrows in Fig. 3. These hot gases are caused to whirl over the surface of the liquid pool and vaporize a portion of the liquid fuel, these gases along with thevaporized fuel being drawn out through annular passage 42 between the ballle and pan and carried upwardly with the air stream through the venturi passage 44 to the combustion zone l2. In this annular Venturi passage 44 the air stream follows theouter wall of housing 4 and the stratification or separation of the air and fuel is maintained to such an extent that ignition does not take place in this passage. It is only when the fuel and air reaches the expanded combustion zone l2 that the fluids mix and combustion takes place. The hot gases drawn down through central opening 31 are practically non-combustible, that is, contain so little oxygen that no combustion can be supported in the space-above the oilpan where the vaporization ofthe fuel is accomplished.

It will be noted that an envelope of the relatively cold combustion air flows along the inner surface of housing'4 and deflector ring 1 so as to protect these metal surfaces and minimize carbonizing along these surfaces. The surfaces of the refractory block 38 are exposed to the greatthe extended heat absorption surface furnished 7 by vanes 48 so as to facilitate the vaporization of the oil. While a relatively high temperature will exist above this oil pan combustion cannot take place due to the absence of oxygen in this zone.

The vaporized fuel will burn in the zone l2 with a blue clean flame, and due to the outer envelope of air relatively no carbon will be formed on the metal surfaces although the flame is apparently in contact therewith.

In order to minimize the mixing of the fluidstreams and present'as little obstruction as possible to the flow of these fluids through the annular venturi M, the outer end portions of bolts 40 are preferably streamj lined. or cut away as best shown at 40' in Fig. 4.

With blower I in operation, the burner can be ignited by removing door 54 of the water-heater (see Fig. l) and applying gases above the burner. While. combustion will at first take place above the pool, this will soon be extinguished by the non-combustible gases drawn down .through central opening 31. Thereafter practically no air will circulate around 'baflle 9 and between the'baflle and pan 8.

According to this improved process of burnburned directly without preliminary vaporization.

I claim:

1. A liquid fuel burner comprising a housing, a pan positioned within the-lower portion of the housing, means for feeding liquid fuel to the pan so as to maintain an exposed shallow pool of substantially constant level therein, an annular baflle member positioned above the pan and centered within the housing so as to provide a narrow annular passage between the baffle and housing, the upper end of the housing terminating in an annular inwardly projecting deflector ring providing an annular inwardly and upwardly expanded mixing and combustion zone above the baffle, and means for forcing air from the lower portion of the upwardly through, the annular passage to the combustion zone, the suction of the air stream through the passage causing a circulation of a portion of the hot combustion gases from combustion zone over the baflle member and downwardly through the central opening in the baflle, thence outwardly over the liquid pool and back together with vaporized oil through the annularpassage to the combustion zone.

2. A liquid fuel burner comprising a housing,

a pan positioned within the lower portion of the housing, means for feeding liquid fuel to the panso, as to maintain an exposed shallow pool of substantially constant level therein, an annular bafiie member positioned above the pan and centered within the housing soas to provide a narrow annular passage between the baflle and housing, the upper end of the housing terminating in an annular inwardly projecting deflector ring providing an annular mixing and combustion zone above the baflle, and means for forcing air upwardly through the annular passage to the combustion zone, the suction of the air stream through the passage causing a circulation of a the central opening pool and back through the annularpassage to a suitable torch to the housing beneath the pan' the , 3 portion of the hot"combustion gases around the bafile member from the combustionzone through in the baffle, over the liquid the combustion zone, the uppersurface' of the pan being provided with a plurality of curved grooves to distribute the liquid,and a plurality of curved vanes projecting abovethe pool adjacent the grooves.

3. A liquid fuel burner comprising a housing,

a pan positioned within the lower portion of the housing, means for feeding liquidfuel to the pan so as to maintain an exposed shallow pool of substantially constant level therein, an annular bafile member positioned above the pan and centered within the housing so as to provide a narrow annular passage between the baffle and housing-the upper end of the housing terminating in an annular inwardly projecting deflector ring providing an annular mixing andfcombustion zone above the baille, and means for forcing air upwardly through the annular passage to the combustion zone, the suction of the air stream through the passage causing a circulation of a portion of the hot combustion gases around the bafile member from the combustion 'zone through the central opening in the baffle, over the liquid. pool and back through the. annular passage to thecombustion zone, the upper surface of the pan being provided witha plurality of curved vanes projecting above the liquid pool.

4. A liquid fuel burner comprising a housing, a panpositioned within the lower portion of the housing, means for feeding liquid fuel to the pan so as to maintain an exposed shallow poolof substantiallyconstant level. therein, an annular baflle member positioned above the panand centered-within the housing so as to providea narrow annular'passage between the baflle and housing, the upper endof the housing terminating in an annular inwardly projecting deflector ring providing an' annular mixing and combustion zone above the bafile, means for forcing air upwardly through the annular passage to the combustion zone, the suction of the air stream.

through the passage causing 'a circulation of a portion of the hot combustion gases around the baffle 'member from the combustion zone through the central opening in the bafile, over the liquid pool and back through the annular passage to the combustion zone, and means positioned between the pan and the lower surface of the battle to cause a whirling ,.distribution.of the hot gases above the pool.

5. A liquid fuel burner comprising a housing, a pan positioned within the housing, means for feeding liquid fuel to. the pan so as to maintain an exposedshallow. pool of substantiallyconstant level therein, a bafile member positioned above thepan, means for forcing airupwardly around the pan and baflle to an upper combustion zone and thereby drawing hot non-combustible gasesover the surface of the pool between the pan and baflle, the upper surface of the pan be-.

ing formed with upwardly projecting vanes to increase the heat-transfer surface and distribute the. hot gases in contact with the pool.

6.- A liquid fuel burner comprising a housing,

l6 and baflle, the baflle comprising a metallic bowl feeding liquid fuel to the pan so as to maintain an exposed shallow pool therein, a baflle member positioned above the pan, means for forcing air upwardly around the pan and battle to an upper combustion zone and thereby drawing hot gases over the surface of the pool between the pan having a central bottom opening, a plurality of screw bolts adjustably projecting through the bowl walls and adapted to center the bowl within the housing and support the bowl in spaced relation above the pan, and an annular refractory body cast within the bowl over the boltheads, the central opening in the refractory body registering with the central opening in the bowl and forming a passage for the hot gases.

8. A liquid fuel burner comprising a housing. having an upwardly projecting annular side wall, a pan centrally positioned within the lower portionof the housing so as to provide a narrow annular air passage between the pan and the side wall of the housing, means for feeding liquid fuel to the pan so as to maintain an exposed shallow poolof substantially constant level therein, an annular baille member positioned above the pan and centered above the housing so as to provide an annular air passage between the baflie and the side wall of the housing as a continuation of the first mentioned annular passage, the upper surface of the baflle sloping upwardly and inwardly, and the upper end of the housing terminating in a deflectorring sloping upwardly and inwardly at 'a greater angle than the opposed surface of the baflie so as to provide a diverging annular mixing and combustion zone above the battle, and means for forcing air into the lower portion of the housing and thence upwardly through the annular air passage to the combustion zone, this annular air stream causing a circulation of a portion of the combustion gases around the baflle member from the combustion zone downwardly through the central, opening in the baflle, over the liquid pool and thence along with oil vaporized by the gases upwardly through the annular passagebetween the air stream and baflle back to. the mixing and combustion zone.

- ALICK CLARKSON. 

